Objects like, for example, automobile bodies, are placed within a paint spray booth in order to be sprayed with paint. Because of the degrading environmental effects paint spray has on the environment, the booths have to be open only on one end and on the back side, i.e., the opposite end from the open end, a suitable filtering and exhaust system has to be incorporated so that air moves at a steady rate from the open side to the back side and all the airborn hydrocarbons would be trapped in the filters before the air is expelled into the atmosphere. Although this system protects the environment, the auto body is not protected from airborn particles already in the atmosphere. These particles are objectionable because they would stick to the tacky painted surface whereby a good finish was impossible to obtain. As an improvement, the open side was covered with a filter so that the already airborn particles may be filtered out. After a while, one finds that the atmosphere is too dirty for these filters over the open side to be very effective.